#include <REGX52.H>

sbit LED = P2 ^ 0;

void Delay(unsigned int t)
{
    while (t--)
        ;
}

void main()
{
    unsigned char Time, i;
    LED = 0;
    while (1)
    {
        for (Time = 0; Time < 100; Time++)
        {
            for (i = 0; i < 20; i++)
            {
                LED = 0;
                Delay(Time);
                LED = 1;
                Delay(100 - Time);
            }
        }
        for (Time = 100; Time > 0; Time--)
        {
            for (i = 0; i < 20; i++)
            {
                LED = 0;
                Delay(Time);
                LED = 1;
                Delay(100 - Time);
            }
        }
    }
}